This invention relates to fluid line couplings and the like for aircraft in particular, where fluid tightness must be maintained while lightness is required and with subjection to flexing and the application of substantial pressure differentials. Reference is made to Letters Patent of the U.S. Pat. No. 2,913,262 wherein a split coupling is disclosed but which did not become commercially successful, as it leaked even under ideal conditions. It is a general object, therefore, to improve upon this patented coupling in which I am co-inventor, and to provide a coupling body with seals that endure fluid tightness and a body that is stressed so as to eliminate distortion within the fluid pressure range to be encountered.
The conditions in which this coupling is used involves confronting tubular members that are to be coupled through the lateral application thereto of a so-called "Split Coupling", herein referred to as a "Clam-Shell Coupling". Couplings of the type under condideration are characterized by mating halves that embrace the opposed ends of confronting tube sections. The seals are also split and carried by the two body halves of the coupling to embrace the opposed tube ends. Elastomer seals therefor have been employed and fabricated as separate replaceable members with compressible interfaces intended to seal. However, the slightest deformation of the body members together with the primitive seal interface designs resulted in leakage. Therefore, it is an object of this invention to (1) provide body members in a configuration what virtually eliminates distortion thereof; and (2) provide seal interengagement wherein the interfaces overlap in a manner to ensure fluid tightness.
Split couplings of the type under consideration have body members that fit together at a diametrically disposed plane of separation. This is also true of the present coupling wherein flat interfaces of the body halves engage one with the other. An object therefore, is to provide a seal configuration conducive to an ensured fluid tightness at diametrically separable interfaces. It is the sealing members herein which project from one or more of the body members and which are overlapped and/or scarfed to have a "chevron" interengagement or the equivalent thereof.
Heretofore, split coupling body members have been subjected to bending stresses with resultant deflection under load, and obviously mechanical and hydraulic failure likely. However, it is an object of this invention to eliminate bending of the coupling body members and to apply tension stresses exclusively. With the present invention greater reliability is achieved, as the coupling body members are essentially hoop-stressed as they are constricted together over the confronting tube sections.
In addition to the elimination of bending stresses and replacement thereof with tension stress application to the coupling body members the said body members are latched with the application of shear stress, it being and object of this invention to augment shear capability so as to strengthen the coupling. It is to be understood that combined stresses are involved. With the present invention, both the hinge and the latch-link for joining the body halves are of multi-shear configuration which multiplies the strength thereof accordingly while distributing the said tension stresses equally over or through the body members. Only a portion of the latch is in compression, and not a critical stress application.
The coupling herein disclosed is a flexible coupling, in that the confronting tube sections are permitted to be displaced a minimum of 4.degree. out of axial alignment with the axis of the closed coupling. To this end it is an object of this invention to provide radial clearance occupied by a reliable annular seal that conforms to the exterior diameter of the tube sections respectively. With the present invention circular integrity of the seal is ensured by the inclusion therein of scarfed overlapping rather than primitive abutted interfacing. Essentially a compressed tongue and groove interengagement, whereby all interstices are occupied by the elastomer of the seal. Accordingly, circular continuity of the seal embracing the tube end is established.
Uniformity of the confronting tube cross sections is essential to a fluid tight connection, and to this end it is an object of this invention to provide reinforcement at each confronting tube end. Heretofore, rolled beads of semi circular arcuate cross sections have been employed as they are disclosed in U.S. Pat. No. 2,913,202; but not so with the present invention wherein an improved "bead-over-wire" reinforcement is employed. This bead-over-wire reinforcement not only makes the tube stiffer but also prevents collapse or crushing, as it eliminates the ramp effect to which the simple prior art bead is subject. Note that force application is normal to this bead-over-wire abutment, at the tangent point of engagement; therefore force application is axial.
Electrical bonding is requirement of tube couplings, and to this end it is an object to provide an improved brush contact between the coupling bodies and outer diameters of the confronting tube ends. The brush of the present invention can vary in configuration, being carried in a groove provided exclusively therefor. A feature of said brush is its circular embracement of the tubing to be bonded, in one form a serpentine wire and in another form a circular pack of radial bristles; in each instance crimped or cemented into the accommodating groove.
It is an object herein to provide the complete coupling having the features hereinabove referred to, in a commercially practical form comprised of the fewest number of members and parts that are not only reliable but conducive to inexpensive fabrication. It is an object to employ extruded body half sections, as well as extruded latch and link members; all of which are subject to simple and accurate machine operations for their completion as operable parts. Accordingly, unnecessary material is removed for lightness, and sized configurations and tolerances established with known and readily applicable machine tools and methods. The seals as later described are molded in place and bonded into the channels provided for their incorporation into the body sections.